Motor Controls 1

Front 1

What do AC Motors do?

Back 1

Transform electrical energy into mechanical energy.

Front 2

What are AC Motors used for?

Back 2

Pumps, fans, conveyors, heating/AC, feeders, mixers, etc.

Front 3

What industry is an induction motor most common in?

Back 3

The manufacturing industry.

Front 4

What are the three main parts of an AC motor?

Back 4

Frame or housing, stator, and rotor.

Front 5

What are the parts of a Motors frame or housing?

Back 5

Housing, mounting or base, connection box, front/rear shield support, and external fan.

Front 6

What does housing do?

Back 6

Protects motor from the environment.

Front 7

What does mounting or base do?

Back 7

Supports the motor.

Front 8

What is the connection box?

Back 8

It protects the electrical connection to the motor.

Front 9

What do the front/rear end shield do?

Back 9

Support the bearings and enclose the ends of the motor.

Front 10

What does the external fan and guard do?

Back 10

Cools motor and protects fan blades.

Front 11

What does TEFC stand for?

Back 11

Totally enclosed fan cooled

Front 12

What is the most common type of motor?

Back 12

TEFC. It's a general motor.

Front 13

What is the stator?

Back 13

It's the stationary functioning part of a motor.

Front 14

What is the stator constructed of?

Back 14

Steel laminations and insulated wire inserted into the slots of the core. This creates the electromagnet.

Front 15

What us the basis for motor operation?

Back 15

The groups of coiled wire that use the electromagnetic field.

Front 16

Where is power attached?

Back 16

To the stator.

Front 17

What is current?

Back 17

The flow of valence electrons.

Front 18

What do flowing electrons generate?

Back 18

A magnetic field, or lines of flux.

Front 19

What does a clamp meter use to pick up current?

Back 19

It uses a torodo (?) coil to pick up the magnetic field.

Front 20

Why does coiled wire generate a bigger magnetic field?

Back 20

Because it has more surface area.

Front 21

How does current flow?

Back 21

Negative to positive.

Front 22

How do valence electrons behave with AC current?

Back 22

They oscillate.

Front 23

Which is safer, AC or DC?

Back 23

Both are dangerous. Neither are safe.

Front 24

What is a motor starter?

Back 24

A contactor plus an overload.

Front 25

What is a contactor?

Back 25

A large relay.

Front 26

How do you tell a contactor from a relay?

Back 26

If it's for over 20 amps it's a contractor, if it's for under 20 amps its a relay.

Front 27

What is voltage comparable to in hydraulics and pneumatics?

Back 27

Pressure.

Front 28

What happens to the magnetic field in AC?

Back 28

It pulses with the sin wave.

Front 29

What is the most common rotor?

Back 29

Squirrel cage rotor.

Front 30

What does 120 offset mean?

Back 30

It means that the motor windings are physically 120 degrees apart.

Front 31

What is the primary production of electricity?

Back 31

Coal.

Front 32

How do transformers work?

Back 32

The magnetic field moves valence electrons on secondary side, producing electricity.

Front 33

What is the rotor also known as?

Back 33

The armature.

Front 34

What is the rotor?

Back 34

The moving part of the motor.

Front 35

How are laminations arranged?

Back 35

In a cone shape.

Front 36

What is the rotor core mounted on?

Back 36

A steel shaft.

Front 37

What are the types of rotors?

Back 37

Squirrel cage and wire wound.

Front 38

What is the deference between a squirrel cage rotor and a wire wound rotor?

Back 38

Squirrel cage uses stack of steel laminations, wire wound uses coils of wire.

Front 39

What is a centrifugal switch used on?

Back 39

Single phase Motors.

Front 40

What is centrifugal start useful for?

Back 40

For when you need more starting torque.

Front 41

Do centrifugal switches stay on the whole time the motor is running?

Back 41

No, they switch off once the motor reaches a certain level of RPM.

Front 42

If a motor is running loudly, what might the problem be?

Back 42

It is single phasing.

Front 43

How can you make a single phase motor work?

Back 43

By using a capacitor.

Front 44

What are capacitors measured in?

Back 44

Farads.

Front 45

What are farads measuring?

Back 45

Time to charge/discharge.

Front 46

What are capacitors used for in single phase Motors?

Back 46

They can be used to offset a phase, which then creates a third phase.

Front 47

Are capacitors used the whole time a motor is on?

Back 47

No, just to start it. It heavily loads one of the original phases.

Front 48

What does the nameplate of a motor contain?

Back 48

Voltage (high/low), Current, phase, frequency, horsepower, speed, max ambient temperature, service factor, NEMA class, duty cycle, thermal protection.

Front 49

What is speed rated in?

Back 49

RPMs.

Front 50

What is service factor?

Back 50

The amount a motor can be safely overloaded.

Front 51

What does NEMA stand for?

Back 51

National electrical manufacturers Association.

Front 52

How are NEMA classifications displayed?

Back 52

Starts off at 00 and goes up.

Front 53

Does a motor pulling the same power as another motor always equal the same amount of voltage and current?

Back 53

No.

Front 54

An AC motor of 200 horsepower and a DC motor of 200 horsepower exist. Which is smaller?

Back 54

The AC motor.

Front 55

Why are DC Motors typically bigger?

Back 55

They have more equipment inside.

Front 56

Does higher voltage always mean less power?

Back 56

No. P=I•E

Front 57

How are you supposed to view motor rotation?

Back 57

From the perspective of the shaft end.

Front 58

What are the speed classifications?

Back 58

Adjustable speed, multiple speed, variable speed, and adjustable/varying speed.

Front 59

What is a characteristic of a multiple speed motor?

Back 59

It has three or more different speeds.

Front 60

What are poles?

Back 60

The coils of the stator.

Front 61

What does more poles equal?

Back 61

More torque lower speed

Front 62

What does less poles equal?

Back 62

Less torque higher speed.

Front 63

What is adjustable speed?

Back 63

You are able to adjust the speed in small increments over a certain range of speeds to adjust for load on motor.

Front 64

What is multiple speed?

Back 64

The motto has multiple speeds that are dependent on which coils are energized.

Front 65

What is variable speed?

Back 65

Speed changes based on load.

Front 66

What are the different service classifications?

Back 66

General use, definite use and special purpose.

Front 67

General use definition

Back 67

Has standard ratings.

Front 68

Definite use definition

Back 68

Restricted to what it can be used on

Front 69

Special purpose definition

Back 69

Has certain design parameters.

Front 70

What is the most common service classification?

Back 70

General purpose.

Front 71

What are the types of housing enclosures?

Back 71

Open and closed.

Front 72

What are some common characteristics of open Motors?

Back 72

General purpose, drip proof, splash proof, not water proof.

Front 73

What is the difference between drip proof and splash proof?

Back 73

Drip proof protects from water coming at an up to 10° angle, splash proof protects up to 100°

Front 74

What is torque?

Back 74

The twisting or turning force on an object to cause it to rotate.

Front 75

How is torque measured?

Back 75

In Ft•Lbs

Front 76

How many ftlbs to an hp?

Back 76

550 ft•lbs/sec to one HP.

Front 77

What is full load torque?

Back 77

The amount of torque needed to supply the rated HP at full speed.

Front 78

What is synchronous speed?

Back 78

The hypothetical speed. Can't reach it.

Front 79

What is slip?

Back 79

The difference between synchronous and rotational speed.

Front 80

How does slip effect torque?

Back 80

Less slip equals more torque.

Front 81

What is synchronous speed related to?

Back 81

The stator.

Front 82

What is rotational speed related to?

Back 82

The rotor.

Front 83

What is slip measured in?

Back 83

Percent.

Front 84

What is full load amps?

Back 84

The current drawn when the motor is putting out the rated HP.

Front 85

What is speed regulation?

Back 85

The kind of speed change you'll have when approaching full load of the motor.

Front 86

Is a higher or lower percentage better when measuring speed regulation?

Back 86

Lower.

Front 87

How many classes of fire hazards are there?

Back 87

Three.

Front 88

What is class one fire hazard?

Back 88

Flammable vapors/gas.

Front 89

What is class two fire hazard?

Back 89

Combustible dust

Front 90

What is class three fire hazard?

Back 90

Ignitable fibers.

Front 91

How fast does a gfci work?

Back 91

In one thirtieth of a second.

Front 92

What is the purpose of a gfci?

Back 92

To protect against electrical shock.

Front 93

What is the purpose of a fuse?

Back 93

To protect the wiring.

Front 94

What does a gfci detect?

Back 94

Leakage current.

Front 95

What is the smallest level of wire gage to use in a grounding wire?

Back 95

14

Front 96

What is ground?

Back 96

The reference for voltage.

Front 97

What do we use the earth as when grounding thinks?

Back 97

A conductor.

Front 98

Are ground and neutral the same point electrically?

Back 98

Yes.

Front 99

What is the main purpose of a ground wire?

Back 99

Safety.

Front 100

What is the difference between ground and neutral wires?

Back 100

Neutral is conducting current, ground is not.

Front 101

Should ground wires be the same length of the other wires?

Back 101

No, they should be longer.